水中爆炸作用下混凝土重力坝损伤研究

Research on damage of concrete gravity dams under underwater explosion

近一个世纪以来,大坝安全逐渐受到各界关注。大坝在极端荷载作用下的动力响应与损伤演化研究是大坝安全问题的基础,近几十年来,学者们对大坝在地震荷载作用下的响应多有研究,但对于爆炸等小概率荷载,试验与理论等方面的研究还有较大的完善空间。以50 m高混凝土重力坝为原型进行1∶20缩比,设计了2.5 m高混凝土重力坝水中爆炸模型试验,分析了试验中水中压力与坝体的加速度响应,讨论了坝前水中爆炸的压力特征与坝体动力响应,并以坝体损伤试验为例建立水中爆炸作用下混凝土重力坝损伤的数值模型,对坝体损伤演化进行了分析。通过对试验与数值模型计算结果分析:发现水中爆炸作用下坝体的动力响应主要由冲击波作用引起,气泡脉动对坝体的加速度响应作用几乎可以忽略不计,且水中爆炸作用下,目标坝体的加速度响应峰值明显大于相邻坝段,坝段之间分缝对相邻坝体的保护作用明显。

Over the past century,dam safety has gradually attracted attention from all walks of life.The research on the dynamic response and damage evolution of dams under extreme loads is the foundation of dam safety issues.In recent decades,scholars have studied the response of dams under earthquake loads,but there is still great room for improvement in research on small probability loads such as explosions,experiments and theories.It takes a 50 m high concrete gravity dam as a prototype and conducts a 1∶20 scaling experiment.A 2.5 m high concrete gravity dam underwater explosion model experiment is designed,and the water pressure and acceleration response of the dam body during the experiment are analyzed.The pressure characteristics of the water explosion in front of the dam and the dynamic response of the dam body are discussed.Taking the dam body damage experiment as an example,a numerical model of concrete gravity dam damage under underwater explosion is established,and the evolution of dam body damage is analyzed.Through the analysis of experimental and numerical model calculation results,it was found that the dynamic response of the dam body under the action of underwater explosions is mainly caused by the action of shock waves,and the acceleration response of bubble pulsation on the dam body can be almost ignored.Moreover,under the action of underwater explosions,the peak acceleration response of the target dam body is significantly greater than that of adjacent dam sections,and the protective effect of joints between dam sections on adjacent dam bodies is obvious.